von Willebrand factor inhibition improves endothelial function in patients with stable angina

Phage Display as a Medium for Target Therapy Based Drug Discovery, Review and Update

Phage libraries are now amongst the most prominent approaches for the identification of high-affinity antibodies/peptides from billions of displayed phages in a specific library through the biopanning process. Due to its ability to discover potential therapeutic candidates that bind specifically to targets, phage display has gained considerable attention in targeted therapy. Using this approach, peptides with high-affinity and specificity can be identified for potential therapeutic or diagnostic use. Furthermore, phage libraries can be used to rapidly screen and identify novel antibodies to develop immunotherapeutics. The Food and Drug Administration (FDA) has approved several phage display-derived peptides and antibodies for the treatment of different diseases. In the current review, we provided a comprehensive insight into the role of phage display-derived peptides and antibodies in the treatment of different diseases including cancers, infectious diseases and neurological disorders. We also explored the applications of phage display in targeted drug delivery, gene therapy, and CAR T-cell.

Dexmedetomidine ameliorates x-ray-induced myocardial injury via alleviating cardiomyocyte apoptosis and autophagy

BACKGROUND

Radiotherapy is a primary local treatment for tumors, yet it may lead to complications such as radiation-induced heart disease (RIHD). Currently, there is no standardized approach for preventing RIHD. Dexmedetomidine (Dex) is reported to have cardio-protection effects, while its role in radiation-induced myocardial injury is unknown. In the current study, we aimed to evaluate the radioprotective effect of dexmedetomidine in X-ray radiation-treated mice.

METHODS

18 male mice were randomized into 3 groups: control, 16 Gy, and 16 Gy + Dex. The 16 Gy group received a single dose of 16 Gy X-ray radiation. The 16 Gy + Dex group was pretreated with dexmedetomidine (30 µg/kg, intraperitoneal injection) 30 min before X-ray radiation. The control group was treated with saline and did not receive X-ray radiation. Myocardial tissues were collected 16 weeks after X-ray radiation. Hematoxylin-eosin staining was performed for histopathological examination. Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining was performed to assess the state of apoptotic cells. Immunohistochemistry staining was performed to examine the expression of CD34 molecule and von Willebrand factor. Besides, western blot assay was employed for the detection of apoptosis-related proteins (BCL2 apoptosis regulator and BCL2-associated X) as well as autophagy-related proteins (microtubule-associated protein 1 light chain 3, beclin 1, and sequestosome 1).

RESULTS

The findings demonstrated that 16 Gy X-ray radiation resulted in significant changes in myocardial tissues, increased myocardial apoptosis, and activated autophagy. Pretreatment with dexmedetomidine significantly protects mice against 16 Gy X-ray radiation-induced myocardial injury by inhibiting apoptosis and autophagy.

CONCLUSION

In summary, our study confirmed the radioprotective effect of dexmedetomidine in mitigating cardiomyocyte apoptosis and autophagy induced by 16 Gy X-ray radiation.

The Multifaceted Effects of Non-Steroidal and Non-Opioid Anti-Inflammatory and Analgesic Drugs on Platelets: Current Knowledge, Limitations, and Future Perspectives

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely utilized pharmaceuticals worldwide. Besides their recognized anti-inflammatory effects, these drugs exhibit various other pleiotropic effects in several cells, including platelets. Within this article, the multifaceted properties of NSAIDs on platelet functions, activation and viability, as well as their interaction(s) with established antiplatelet medications, by hindering several platelet agonists' pathways and receptors, are thoroughly reviewed. The efficacy and safety of NSAIDs as adjunctive therapies for conditions involving inflammation and platelet activation are also discussed. Emphasis is given to the antiplatelet potential of commonly administered NSAIDs medications, such as ibuprofen, diclofenac, naproxen and ketoprofen, alongside non-opioid analgesic and antipyretic medications like paracetamol. This article delves into their mechanisms of action against different pathways of platelet activation, aggregation and overall platelet functions, highlighting additional health-promoting properties of these anti-inflammatory and analgesic agents, without neglecting the induced by these drugs' side-effects on platelets' functionality and thrombocytopenia. Environmental issues emerging from the ever-increased subscription of these drugs are also discussed, along with the need for novel water treatment methodologies for their appropriate elimination from water and wastewater samples. Despite being efficiently eliminated during wastewater treatment processes on occasion, NSAIDs remain prevalent and are found at significant concentrations in water bodies that receive effluents from wastewater treatment plants (WWTPs), since there is no one-size-fits-all solution for removing all contaminants from wastewater, depending on the specific characteristics of the wastewater. Several novel methods have been studied, with adsorption being proposed as a cost-effective and environmentally friendly method for wastewater purification from such drugs. This article also presents limitations and future prospects regarding the observed antiplatelet effects of NSAIDs, as well as the potential of novel derivatives of these compounds, with benefits in other important platelet functions.

Cadmium, von Willebrand factor and vascular aging

Vascular aging is a major contributing factor to cardiovascular disease. The aged blood vessels, characterized by vascular wall thickening and stiffening, are instigated by endothelial cell dysfunction induced by oxidative stress and inflammation. von Willebrand Factor (vWF) is a glycoprotein known for its role in coagulation, and plasma levels of vWF are increased with age. Elevated vWF promotes thrombosis, atherosclerotic plaque formation, inflammation and proliferation of vascular smooth muscle cells. Cadmium (Cd) is an environmental pollutant associated with increased morbidity and mortality of cardiovascular disease. At low concentrations, Cd activates pro-survival signaling in endothelial cells, however enhances intima-media thickness and atherogenesis. A non-cytotoxic dose of Cd also increases endothelial vWF expression and secretion in vivo and in vitro. In this review, we summarize the molecular mechanisms underlying vWF-promoted vascular aging-associated pathologies and Cd-induced vWF expression. In addition, we propose that exposure to low-dose Cd is a risk factor for vascular aging, through elevation of plasma vWF.

Caplacizumab for treating subacute intra-stent thrombus occurring despite efficacious double anti-platelet treatment and anticoagulation: a case report

Background

Acute and subacute stent thromboses are a rare complication associated with high mortality and morbidity occurring in ∼1.5% of patients treated with primary percutaneous intervention for ST-elevation myocardial infarction (STEMI). Recent publications describe a potential role of the von Willebrand factor (VWF) in thrombus formation at sites of critical coronary stenosis in STEMI.

Case summary

We describe a 58-year-old woman with STEMI at initial presentation, who suffered subacute stent thrombosis despite good stent expansion, efficacious dual antiplatelet therapy, and therapeutic anticoagulation. Because of very high VWF values, we administered N-acetylcysteine in order to depolymerize VWF, but the drug was not well tolerated. Since the patient was still symptomatic, we used caplacizumab in order to prevent VWF from interacting with platelets. Under this treatment, the clinical and angiographic course was favourable.

Discussion

Considering a modern view of intracoronary thrombus pathophysiology, we describe an innovative treatment approach, which eventually ended in a favourable outcome.

von Willebrand Factor Predicts Mortality in ACS Patients Treated with Potent P2Y12 Antagonists and is Inhibited by Aptamer BT200 Ex Vivo

BACKGROUND

 von Willebrand factor (VWF) is crucial for arterial thrombosis and its plasma levels are increased in acute coronary syndromes (ACSs). The effects of conventional platelet inhibitors are compromised by elevated VWF under high shear rates. BT200 is a third-generation aptamer that binds and inhibits the A1 domain of human VWF. This article aims to study whether VWF is a predictor of mortality in ACS patients under potent P2Y12 blocker therapy and to examine the effects of a VWF inhibiting aptamer BT200 and its concentrations required to inhibit VWF in plasma samples of patients with ACS.

METHODS

 VWF activity was measured in 320 patients with ACS, and concentration effect curves of BT200 were established in plasma pools containing different VWF concentrations.

RESULTS

 Median VWF activity in patients was 170% (interquartile range % confidence interval [CI]: 85-255) and 44% of patients had elevated (> 180%) VWF activity. Plasma levels of VWF activity predicted 1-year (hazard ratio [HR]: 2.68; 95% CI: 1.14-6.31; p < 0.024) and long-term (HR: 2.59; 95% CI: 1.10-6.09) mortality despite treatment with potent platelet inhibitors (dual-antiplatelet therapy with aspirin and prasugrel or ticagrelor). Although half-maximal concentrations were 0.1 to 0.2 µg/mL irrespective of baseline VWF levels, increasing concentrations (0.42-2.13 µg/mL) of BT200 were needed to lower VWF activity to < 20% of normal in plasma pools containing increasing VWF activity (p < 0.001).

CONCLUSION

 VWF is a predictor of all-cause mortality in ACS patients under contemporary potent P2Y12 inhibitor therapy. BT200 effectively inhibited VWF activity in a target concentration-dependent manner.

Caplacizumab in adult patients with acquired thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is usually a fatal disease caused by a deficiency of the metalloproteinase, ADAMTS13, often due to autoimmunity. This leads to the development of pathogenic multimers of von Willebrand factor (vWF), causing an inappropriate interaction of platelets and vWF. This results in a thrombotic microangiopathy, which is treated with therapeutic plasma exchange and immune suppression. Although this treatment has reduced the mortality of TTP to only about 20%, there have been no recent significant advances in the treatment of TTP. Recently, a novel agent has been approved for use in TTP. Caplacizumab, which binds to the A1 domain of vWF, prevents the adhesion of platelets to vWF. It is a first in-class ‘nanobody’, that in clinical trials has shown marked efficacy in treating TTP and its complications. This review will discuss the development and implications of caplacizumab in the treatment of TTP.

Antithrombotic Therapy: Prevention and Treatment of Atherosclerosis and Atherothrombosis

Atherosclerosis is a multifactorial vascular disease that develops in the course of a lifetime. Numerous risk factors for atherosclerosis have been identified, mostly inflicting pro-inflammatory effects. Vessel injury, such as occurring during erosion or rupture of atherosclerotic lesions triggers blood coagulation, in attempt to maintain hemostasis (protect against bleeding). However, thrombo-inflammatory mechanisms may drive blood coagulation such that thrombosis develops, the key process underlying myocardial infarction and ischemic stroke (not due to embolization from the heart). In the blood coagulation system, platelets and coagulation proteins are both essential elements. Hyperreactivity of blood coagulation aggravates atherosclerosis in preclinical models. Pharmacologic inhibition of blood coagulation, either with platelet inhibitors, or better documented with anticoagulants, or both, limits the risk of thrombosis and may potentially reverse atherosclerosis burden, although the latter evidence is still based on animal experimentation.Patients at risk of atherothrombotic complications should receive a single antiplatelet agent (acetylsalicylic acid, ASA, or clopidogrel); those who survived an atherothrombotic event will be prescribed temporary dual antiplatelet therapy (ASA plus a P2Y12 inhibitor) in case of myocardial infarction (6-12 months), or stroke (<6 weeks), followed by a single antiplatelet agent indefinitely. High risk for thrombosis patients (such as those with peripheral artery disease) benefit from a combination of an anticoagulant and ASA. The price of gained efficacy is always increased risk of (major) bleeding; while tailoring therapy to individual needs may limit the risks to some extent, new generations of agents that target less critical elements of hemostasis and coagulation mechanisms are needed to maintain efficacy while reducing bleeding risks.

Progress in the development of antiplatelet agents: Focus on the targeted molecular pathway from bench to clinic

Antiplatelet drugs serve as a first-line antithrombotic therapy for the management of acute ischemic events and the prevention of secondary complications in vascular diseases. Numerous antiplatelet therapies have been developed; however, currently available agents are still associated with inadequate efficacy, risk of bleeding, and variability in individual response. Understanding the mechanisms of platelet involvement in thrombosis and the clinical development process of antiplatelet agents is critical for the discovery of novel agents. The functions of platelets in thrombosis are regulated by two major mechanisms: the interaction between surface receptors and their ligands, and the downstream intracellular signaling pathways. Recently, most of the progress made in antiplatelet drug development has been achieved with P2Y receptor antagonists. Additionally, the usage of GP IIb/IIIa receptor antagonists has decreased, because it is associated with a higher risk of bleeding and thrombocytopenia. Agents targeting other platelet surface receptors such as PARs, TP receptor, EP3 receptor, GPIb-IX-V receptor, P-selectin, as well as intracellular signaling factors, such as PI3Kβ, have been evaluated in an attempt to develop the next generation of antiplatelet drugs, reduce or eliminate interpatient variability of drug efficacy and significantly lower the risk of drug-induced bleeding. The aim of this review is to describe the pathways of platelet activation in thrombosis, and summarize the development process of antiplatelet agents, as well as the preclinical and clinical evaluations performed on these agents.

Novel Antiplatelet Therapies for Atherothrombotic Diseases

Antiplatelet therapies are an essential tool to reduce the risk of developing clinically apparent atherothrombotic disease and are a mainstay in the therapy of patients who have established cardiovascular, cerebrovascular, and peripheral artery disease. Strategies to intensify antiplatelet regimens are limited by concomitant increases in clinically significant bleeding. The development of novel antiplatelet therapies targeting additional receptor and signaling pathways, with a focus on maintaining antiplatelet efficacy while preserving hemostasis, holds tremendous potential to improve outcomes among patients with atherothrombotic diseases.

Investigational drugs for the treatment of acute myocardial infarction: focus on antiplatelet and anticoagulant agents

BACKGROUND

Advances in our understanding of the complex pathophysiologic mechanisms responsible for high-risk atherosclerotic plaque rupture resulting in acute myocardial infarction (AMI) have led to the development of numerous antiplatelet and anticoagulant agents for treatment of AMI.

AREAS COVERED

We review various antithrombotic drugs which were recently investigated for the treatment of AMI. A MEDLINE search for relevant articles on newer antiplatelet agents and anticoagulants drugs for the treatment of AMI was performed, and important original investigations were reviewed. We also briefly discuss agents that completed evaluation and were recently recommended by expert guidelines.

EXPERT OPINION

The antiplatelet agents cangrelor and vorapaxar and the anticoagulant rivaroxaban, have shown promise for the reduction of ischemic events when administered during, and in the acute phase following AMI. However, these agents have not been compared with more potent P2Y12 inhibitors, prasugrel, and ticagrelor. Finding an optimum combination of these agents to achieve an appropriate risk (bleeding) - benefit (reduction in ischemic events) balance is challenging. Further evaluation of agents that show promise is important for enhancing our armamentarium of pharmacologic agents for the successful treatment of AMI.

Platelet pathophysiology, pharmacology, and function in coronary artery disease

Platelets play a key role in the pathophysiology of coronary artery disease and acute coronary syndromes. Our understanding of platelet function in thrombus formation has increased considerably, resulting in the development of clinically effective treatment strategies and identification of new targets. An underappreciated platelet function is their contribution toward acute and chronic inflammatory processes including atherogenesis. In this review, we discuss the role of platelets in atherosclerosis and thrombosis, platelet function testing, and the pharmacology of currently available antiplatelet drugs.

New insights into the non-hemostatic role of von Willebrand factor in endothelial protection

During exposure to ischemia-reperfusion (I/R) insult, angiotensin II (AngII)-induced endothelin-1 (ET-1) upregulation in endothelial cells progressively impairs nitric oxide (NO) bioavailability while increasing levels of superoxide anion (O₂^-) and leading to the onset of endothelial dysfunction. Moreover, the overexpression of ET-1 increases the endothelial and circulating levels of von Willebrand factor (vWF), a glycoprotein with a crucial role in arterial thrombus formation. Nowadays, the non-hemostatic role of endothelial vWF is emerging, although we do not yet know whether its increased expression is cause or consequence of endothelial dysfunction. Notably, the vWF blockade or depletion leads to endothelial protection in cultured cells, animal models of vascular injury, and patients as well. Despite the recent efforts to develop an effective pharmacological strategy, the onset of endothelial dysfunction is still difficult to prevent and remains closely related to adverse clinical outcome. Unraveling the non-hemostatic role of endothelial vWF in the onset of endothelial dysfunction could provide new avenues for protection against vascular injury mediated by AngII.

Thrombin generation test for evaluation of antiplatelet treatment in patients with coronary artery disease after percutaneous coronary intervention

To study the possibility of using thrombin generation tests in platelet-rich and platelet-poor plasma for evaluation of dual antiplatelet therapy efficacy in patients with coronary artery disease (CAD), following percutaneous coronary intervention. Venous blood was analyzed from CAD patients aged 53-75 years who had undergone percutaneous coronary intervention with stenting within one year and had been receiving standard doses of clopidogrel and aspirin (75 and 75-100 mg per day, respectively). The control group comprised age- and sex-matched subjects without clinical signs of CAD who were not receiving these drugs. Thrombin generation tests were performed in platelet-rich and platelet-poor plasma. Intravascular platelet activation, induced platelet aggregation, and routine coagulation were evaluated. Antiplatelet treatment did not influence results of routine coagulation tests or intravascular platelet activation. The dual antiplatelet therapy affects collagen-induced platelet aggregation (44 ± 2.5 vs. 7.9 ± 2.6%, р = 10^-7) and leads to decreases in endogenous thrombin potential (1900 ± 85 vs. 1740 ± 95 nM∙min, p = 0.0045), maximum thrombin concentration (134 ± 9.5 vs. 106 ± 6.5 nM, p = 4∙10^-6), and increases in time to peak thrombin (27 ± 1.5 vs. 31 ± 2 min, p = 0.0012). Decreases in thrombin generation rate showed the highest statistical significance (13 ± 2 vs. 7.9 ± 0.8 nM/min, p = 10^-8). Antiplatelet treatment did not alter thrombogram parameters for platelet-poor plasma.

Platelets and platelet adhesion molecules: novel mechanisms of thrombosis and anti-thrombotic therapies

Platelets are central mediators of thrombosis and hemostasis. At the site of vascular injury, platelet accumulation (i.e. adhesion and aggregation) constitutes the first wave of hemostasis. Blood coagulation, initiated by the coagulation cascades, is the second wave of thrombin generation and enhance phosphatidylserine exposure, can markedly potentiate cell-based thrombin generation and enhance blood coagulation. Recently, deposition of plasma fibronectin and other proteins onto the injured vessel wall has been identified as a new "protein wave of hemostasis" that occurs prior to platelet accumulation (i.e. the classical first wave of hemostasis). These three waves of hemostasis, in the event of atherosclerotic plaque rupture, may turn pathogenic, and cause uncontrolled vessel occlusion and thrombotic disorders (e.g. heart attack and stroke). Current anti-platelet therapies have significantly reduced cardiovascular mortality, however, on-treatment thrombotic events, thrombocytopenia, and bleeding complications are still major concerns that continue to motivate innovation and drive therapeutic advances. Emerging evidence has brought platelet adhesion molecules back into the spotlight as targets for the development of novel anti-thrombotic agents. These potential antiplatelet targets mainly include the platelet receptors glycoprotein (GP) Ib-IX-V complex, β3 integrins (αIIb subunit and PSI domain of β3 subunit) and GPVI. Numerous efforts have been made aiming to balance the efficacy of inhibiting thrombosis without compromising hemostasis. This mini-review will update the mechanisms of thrombosis and the current state of antiplatelet therapies, and will focus on platelet adhesion molecules and the novel anti-thrombotic therapies that target them.

Gene silencing of endothelial von Willebrand Factor attenuates angiotensin II-induced endothelin-1 expression in porcine aortic endothelial cells

Expression of endothelin (ET)-1 is increased in endothelial cells exposed to angiotensin II (Ang II), leading to endothelial dysfunction and cardiovascular disorders. Since von Willebrand Factor (vWF) blockade improves endothelial function in coronary patients, we hypothesized that targeting endothelial vWF with short interference RNA (siRNA) prevents Ang II-induced ET-1 upregulation. Nearly 65 ± 2% silencing of vWF in porcine aortic endothelial cells (PAOECs) was achieved with vWF-specific siRNA without affecting cell viability and growth. While showing ET-1 similar to wild type cells at rest, vWF-silenced cells did not present ET-1 upregulation during exposure to Ang II (100 nM/24 h), preserving levels of endothelial nitric oxide synthase activity similar to wild type. vWF silencing prevented AngII-induced increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activity and superoxide anion (O2-) levels, known triggers of ET-1 expression. Moreover, no increase in O2- or ET-1 levels was found in silenced cells treated with AngII or NOX-agonist phorbol ester (PMA 5 nM/48 h). Finally, vWF was required for overexpression of NOX4 and NOX2 in response to AngII and PMA. In conclusion, endothelial vWF knockdown prevented Ang II-induced ET-1 upregulation through attenuation of NOX-mediated O2- production. Our findings reveal a new role of vWF in preventing of Ang II-induced endothelial dysfunction.

EGFR targeted nanobody-photosensitizer conjugates for photodynamic therapy in a pre-clinical model of head and neck cancer

Photodynamic therapy (PDT) induces cell death through local light activation of a photosensitizer (PS) and has been used to treat head and neck cancers. Yet, common PS lack tumor specificity, which leads to collateral damage to normal tissues. Targeted delivery of PS via antibodies has pre-clinically improved tumor selectivity. However, antibodies have long half-lives and relatively poor tissue penetration, which could limit therapeutic efficacy and lead to long photosensitivity. Here, in this feasibility study, we evaluate at the pre-clinical level a recently introduced format of targeted PDT, which employs nanobodies as targeting agents and a water-soluble PS (IRDye700DX) that is traceable through optical imaging. In vitro, the PS solely binds to cells and induces phototoxicity on cells overexpressing the epidermal growth factor receptor (EGFR), when conjugated to the EGFR targeted nanobodies. To investigate whether this new format of targeted PDT is capable of inducing selective tumor cell death in vivo, PDT was applied on an orthotopic mouse tumor model with illumination at 1h post-injection of the nanobody-PS conjugates, as selected from quantitative fluorescence spectroscopy measurements. In parallel, and as a reference, PDT was applied with an antibody-PS conjugate, with illumination performed 24h post-injection. Importantly, EGFR targeted nanobody-PS conjugates led to extensive tumor necrosis (approx. 90%) and almost no toxicity in healthy tissues, as observed through histology 24h after PDT. Overall, results show that these EGFR targeted nanobody-PS conjugates are selective and able to induce tumor cell death in vivo. Additional studies are now needed to assess the full potential of this approach to improving PDT.

Advances in induced pluripotent stem cells, genomics, biomarkers, and antiplatelet therapy highlights of the year in JCTR 2013

The Journal provides the clinician and scientist with the latest advances in discovery research, emerging technologies, preclinical research design and testing, and clinical trials. We highlight advances in areas of induced pluripotent stem cells, genomics, biomarkers, multimodality imaging, and antiplatelet biology and therapy. The top publications are critically discussed and presented along with anatomical reviews and FDA insight to provide context.

Expression profile of neuro-endocrine-immune network in rats with vascular endothelial dysfunction

This study was to determine the correlation between endothelial function and neuro-endocrine-immune (NEI) network through observing the changes of NEI network under the different endothelial dysfunction models. Three endothelial dysfunction models were established in male Wistar rats after exposure to homocysteine (Hcy), high fat diet (HFD) and Hcy+HFD. The results showed that there was endothelial dysfunction in all three models with varying degrees. However, the expression of NEI network was totally different. Interestingly, treatment with simvastatin was able to improve vascular endothelial function and restored the imbalance of the NEI network, observed in the Hcy+HFD group. The results indicated that NEI network may have a strong association with endothelial function, and this relationship can be used to distinguish different risk factors and evaluate drug effects.

Novel antiplatelet agents: ALX-0081, a Nanobody directed towards von Willebrand factor

This manuscript reviews the studies performed with ALX-0081 (INN: caplacizumab), a Nanobody targeting von Willebrand factor, in the context of current antithrombotic therapy in coronary artery disease. ALX-0081 specifically inhibits platelet adhesion to the vessel wall, and may control platelet aggregation and subsequent clot formation without increasing bleeding risk. A substantial number of antithrombotics are aimed at this cascade; however, their generally indiscriminative mode of action can result in a narrow therapeutic window, defined by the risk for bleeding complications, and thrombotic events. Nonclinically, ALX-0081 compared favorably to several antithrombotics. In Phase I studies in healthy subjects and stable angina patients undergoing percutaneous coronary intervention (PCI), ALX-0081 was well tolerated, and effectively inhibited pharmacodynamic markers. Following these results, a phase II study was initiated in high-risk acute coronary syndrome patients undergoing PCI. Based on its mechanism of action, ALX-0081 is also being developed for acquired thrombotic thrombocytopenic purpura.